The invention relates to field machines which have steering units that are controlled by signals from sensors; the sensors may detect the working edge of the field, such as the boundary between plowed and unplowed ground or the boundary between harvested and unharvested areas of a field.
Applicant is aware of German Patent publication 197 03 846.8 and U.S. Pat. Nos. 3,991,618; 4,263,979 and 5,303,636, the disclosures of which are incorporated by reference herein.
U.S. Pat. No. 3,991,618 discloses a device for detecting the working edge of a field. The disclosed sensor unit has an array of sensors which are placed at various points of the harvesting machine, i.e., the sensors are located at the front and back of the machine, and are mounted in close proximity to the ground. The sensors are touch sensitive; they incorporate a feeler arm which detects the presence or absence of the crop. The signal produced by the sensors is supplied to a steering control unit thereby automatically guiding the machine along the working edge of the field. A disadvantage of the known device is that it requires a plurality of sensors located at different positions, so the device is relatively expensive. The sensors also suffer undesirable wear and tear because of the mechanical stresses to which they are subjected. Due to their close proximity to the ground, there is a risk of them being damaged by unpredictable external effects. The present invention may minimize these risks.
The present invention relates to a sensor unit mounted on a field machine, in which a signal produced by the sensor unit is conveyed to a steering control unit for guiding the field machine along a working edge of the field. More particularly, the present invention provides a means for automatically aligning the field machine and sensor unit with a reference point or a reference line and to an alignment method. The invention includes an adjusting device for the sensor unit. Further, an optical display or indicator unit is coupled to the sensor unit such that, in a starting position of the field machine, and at other times, the horizontal and/or vertical alignment of the field machine and sensor unit relative to the working edge of the field may be indicated by the indicator element or display.
The adjusting device and the sensor unit may be mounted on a retaining arm extending transversely to the direction of movement of the machine, or extending perpendicularly. Loosening of the sensor unit in the mount allows the sensor unit to be simultaneously rotated about, and moved in a straight line along, the retaining, arm to provide an initial setting for example.
The method and apparatus in accordance with the invention may also provide automatic aligning or realigning of the field machine and the sensor unit with a reference point or a reference line. The particular advantage of the method according to the invention is that the setting for the adjustment of the sensor unit can be detected and fixed by using electronic means that are provided for other purposes. Positioning means may be associated with the field machine, and the sensor unit for displacing the sensor unit horizontally and/or vertically. These positioning means maybe controlled, at least in part, by a central processing unit. The signal produced by the sensor unit is evaluated in this central processing unit, and the field machine and the sensor unit is then moved in dependence thereon until a correct position is reached, as denoted by the detection of a reference point or a reference line.
Consequently, one object of the present invention is to provide a method of adjusting a sensor unit mounted on a field machine which allows the state of adjustment of the sensor unit to be detected and set in a simple manner.
Further advantages and objects of the invention will be apparent by reference to the drawings, the Description of the Drawings and the Detailed Description of the Invention.